Multi-Echo PRESTO MRI Sequence for Reducing Scan Time
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Solution Overview
Problem
Current magnetic resonance imaging techniques require multiple sequential imaging sequences for diffusion-weighted and other weighted imaging, increasing the overall scanning time and reducing patient throughput due to limitations in echo times and the need for separate sequences.
Innovation Solution
A new multi-echo magnetic resonance imaging technique that applies a series of radio frequency pulses with readout and refocusing gradient pulses to induce and shift gradient echoes, allowing multiple echoes to be measured within a single repetition time, enabling independent echo time and diffusion weighting, and combining multiple sequences into a single sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple sequential imaging sequences are performed for diffusion-weighted and other weighted imaging, then comprehensive imaging coverage is achieved, but overall imaging time increases and patient throughput decreases
Solution Approach 1:
The patent combines multiple separate imaging sequences (diffusion-weighted imaging, T1-weighted imaging, T2-weighted imaging) into a single multi-echo imaging sequence. By acquiring multiple echoes with different weighting characteristics within one sequence using a single radio frequency pulse, the system achieves comprehensive imaging coverage without performing multiple sequential sequences, thereby reducing total imaging time and improving patient throughput
2Adaptability or versatility
If multiple sequential imaging sequences are performed for different weighting types, then comprehensive tissue characterization is achieved, but patient throughput decreases
Solution Approach 1:
The patent merges multiple imaging sequences targeting different tissue characteristics into one unified multi-echo sequence. By utilizing multiple echoes acquired within a single repetition time, the system simultaneously obtains diffusion-weighted, T1-weighted, and T2-weighted images, achieving comprehensive tissue characterization while increasing patient throughput by reducing the number of sequential scans required
3Measurement precision
If echo time is extended for diffusion weighted imaging, then diffusion contrast is improved, but the sequence becomes limited to single echo per TR
Solution Approach 1:
The patent implements periodic action by acquiring multiple echoes at different time points within a single repetition time. The sequence structure uses periodic gradient pulses and echo acquisition windows, allowing the system to capture both long-echo-time signals for diffusion weighting and shorter-echo-time signals for other weightings, thereby maintaining diffusion contrast while enabling multi-echo capability
4Loss of time
If multiple echoes are acquired within a single TR, then imaging time is reduced, but gradient pulse sequencing becomes complex
Solution Approach 1:
The patent applies segmentation by dividing the gradient pulse sequence into distinct segments, each responsible for generating specific echoes with particular weighting characteristics. The gradient waveform is segmented into diffusion-sensitizing portions and readout portions, allowing systematic control of multiple echoes within one TR while managing sequence complexity through structured organization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces imaging time, enhances patient throughput, and allows for the reconstruction of a wide range of neurological and oncological images efficiently using existing hardware, while providing flexible diffusion weighting and phase contrast independent of repetition time.
Implementation Method 1
Magnetic resonance excites resonance in a subject by using a radio frequency pulse
Implementation Method 2
Gradient fields are magnetic fields applied by one or more gradient coils which can refocus or spatially encode the magnetic resonance in a specific volume
Implementation Method 3
As the magnetic resonance naturally decays between pulses, induced magnetic resonance echoes are received by radio frequency coils
Data Source
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AI summary
A magnetic resonance imaging system (78) includes a magnetic resonance imaging device (80), one or more processors (104), and a display (106). The magnetic resonance imaging device (80) includes a magnet (82), gradient coils (88), and one or more radio frequency coils (92). The magnet (82) generates a Bo field. The gradient coils (88) apply gradient fields to the Bo field. The one or more radio frequency coils (92) generate a radio frequency pulse to excite magnetic resonance and measure generated gradient echoes. The one or more processors (104) are configured to activate (116) the one or more radio frequency coils (92) to generate a series of radio frequency pulses spaced by repetition times and to induce magnetic resonance. The one or more processors (104) are configured to control (118) the gradient coils to apply after each RF pulse readout gradient field pulses which refocus the resonance into a plurality of gradient echoes, shift and refocus gradient field pulses which shift and refocus at least one of the echoes to a subsequent repetition time, and receive and demodulate the gradient echoes to form k- space data lines. The one or more processors are configured to reconstruct (124) one or more images from the measured one or more gradient echoes. A display (106) displays the one or more reconstructed images.